1. Field of the Invention
This invention relates to a zoom lens including an area of a shorter distance than the close end of a normal photographing distance range including infinity, that is, a zoom lens which enables distance adjustment in a so-called macro photographing distance range.
2. Description of the Prior Art
In the mechanism in a zoom lens for macro photography, there are a system designed so that a macro photographing distance range and a normal photographing distance range exist continuously within a range obtained by the operation of a ring for adjusting the photographing distance and a system for obtaining a high magnification by moving a plurality of lens groups during macro photography. However, the former is usually an extension of focusing and therefore has a disadvantage that a sufficiently high magnification cannot be obtained, and the latter having a special mechanism is often adopted in zoom lenses capable of macro photography.
It is ideally desirable that macro photography be possible over the whole range of zooming area, but actually, the eclipse of the light beam in a part of the zooming area, the reduction in optical performance and the collision between lenses make macro photography almost impossible in such a zooming area. Accordingly, there have been zoom lenses of a structure in which macro photography is possible only at the long focus side end point or the short focus side end point of the zooming area.